Methods and apparatuses for mechanical and chemical-mechanical planarization of microelectronic-device substrate assemblies on planarizing pads

ABSTRACT

Apparatuses and methods for planarizing a microelectronic-device substrate assembly on a planarizing pad. In one aspect of the invention, material is removed from the substrate assembly by pressing the substrate assembly against a planarizing surface of a planarizing pad and moving the substrate assembly across the planarizing surface through a planarizing zone. The method also includes replacing at least a portion of a used volume of planarizing solution on the planarizing surface with fresh planarizing solution during the planarization cycle of a single substrate assembly. The used planarizing solution can be replaced with fresh planarizing solution by actively removing the used planarizing solution from the pad with a removing unit and depositing fresh planarizing solution onto the pad in the planarizing zone. The used planarizing solution, for example, can be removed either while the substrate assembly is moved through the planarizing zone, or between planarizing stages of a multi-stage planarizing process. In another aspect of the invention, a planarizing machine for planarizing microelectronic-device substrate assemblies includes removing unit at the accumulation zone to actively remove used planarizing solution from the accumulation zone on the stationary planarizing pad.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of pending U.S. patent application Ser.No. 09/854,390, filed May 11, 2001, which is a continuation of U.S.patent application Ser. No. 09/164,915, filed Oct. 1, 1998, issued Jun.26, 2001 as U.S. Pat. No. 6,250,994.

TECHNICAL FIELD

The present invention relates to methods and apparatuses for planarizingmicroelectronic-device substrate assemblies, and to methods formechanical and chemical-mechanical planarization of such substrateassemblies on planarizing pads.

BACKGROUND OF THE INVENTION

Mechanical and chemical-mechanical planarizing processes (“CMP”) areused in the manufacturing of electronic devices for forming a flatsurface on semiconductor wafers, field emission displays and many othermicroelectronic-device substrate assemblies. CMP processes generallyremove material from a substrate assembly to create a highly planarsurface at a precise elevation in the layers of material on thesubstrate assembly.

FIG. 1 schematically illustrates an existing web-format planarizingmachine 10 for planarizing a substrate 12. The planarizing machine 10has a support table 14 with a top-panel 16 at a workstation where anoperative portion (A) of a planarizing pad 40 is positioned. Thetop-panel 16 is generally a rigid plate to provide a flat, solid surfaceto which a particular section of the planarizing pad 40 may be securedduring planarization.

The planarizing machine 10 also has a plurality of rollers to guide,position and hold the planarizing pad 40 over the top-panel 16. Therollers include a supply roller 20, first and second idler rollers 21 aand 21 b, first and second guide rollers 22 a and 22 b, and a take-uproller 23. The supply roller 20 carries an unused or pre-operativeportion of the planarizing pad 40, and the take-up roller 23 carries aused or post-operative portion of the planarizing pad 40. Additionally,the first idler roller 21 a and the first guide roller 22 a stretch theplanarizing pad 40 over the top-panel 16 to hold the planarizing pad 40stationary during operation. A motor (not shown) drives at least one ofthe supply roller 20 and the take-up roller 23 to sequentially advancethe planarizing pad 40 across the top-panel 16. As such, cleanpre-operative sections of the planarizing pad 40 may be quicklysubstituted for used sections to provide a consistent surface forplanarizing and/or cleaning the substrate 12.

The web-format planarizing machine 10 also has a carrier assembly 30that controls and protects the substrate 12 during planarization. Thecarrier assembly 30 generally has a substrate holder 32 to pick up, holdand release the substrate 12 at appropriate stages of the planarizingcycle. A plurality of nozzles 33 attached to the substrate holder 32dispense a planarizing solution 44 onto a planarizing surface 42 of theplanarizing pad 40. The carrier assembly 30 also generally has a supportgantry 34 carrying a drive assembly 35 that translates along the gantry34. The drive assembly 35 generally has an actuator 36, a drive shaft 37coupled to the actuator 36, and an arm 38 projecting from the driveshaft 37. The arm 38 carries the substrate holder 32 via another shaft39 such that the drive assembly 35 orbits the substrate holder 32 aboutan axis B—B offset from a center point C—C the substrate 12.

The planarizing pad 40 and the planarizing solution 44 define aplanarizing medium that mechanically and/or chemically-mechanicallyremoves material from the surface of the substrate 12. The planarizingpad 40 used in the web-format planarizing machine 10 is typically afixed-abrasive planarizing pad in which abrasive particles are fixedlybonded to a suspension material. In fixed-abrasive applications, theplanarizing solution is a “clean solution” without abrasive particlesbecause the abrasive particles are fixedly distributed across theplanarizing surface 42 of the planarizing pad 40. In other applications,the planarizing pad 40 may be a non-abrasive pad without abrasiveparticles composed of a polymeric material (e.g., polyurethane) or othersuitable materials. The planarizing solutions 44 used with thenon-abrasive planarizing pads are typically CMP slurries with abrasiveparticles and chemicals to remove material from a substrate.

To planarize the substrate 12 with the planarizing machine 10, thecarrier assembly 30 presses the substrate 12 against the planarizingsurface 42 of the planarizing pad 40 in the presence of the planarizingsolution 44. The drive assembly 35 then orbits the substrate holder 32about the offset axis B—B to translate the substrate 12 across theplanarizing surface 42. As a result, the abrasive particles and/or thechemicals in the planarizing medium remove material from the surface ofthe substrate 12.

CMP processes should consistently and accurately produce a uniformlyplanar surface on the substrate assembly to enable precise fabricationof circuits and photo-patterns. During the fabrication of transistors,contacts, interconnects and other features, many substrate assembliesdevelop large “step heights” that create a highly topographic surfaceacross the substrate assembly. Yet, as the density of integratedcircuits increases, it is necessary to have a planar substrate surfaceat several stages of processing the substrate assembly becausenon-uniform substrate surfaces significantly increase the difficulty offorming sub-micron features. For example, it is difficult to accuratelyfocus photo-patterns to within tolerances approaching 0.1 μm onnon-uniform substrate surfaces because sub-micron photolithographicequipment generally has a very limited depth of field. Thus, CMPprocesses are often used to transform a topographical substrate surfaceinto a highly uniform, planar substrate surface.

In the competitive semiconductor industry, it is also highly desirableto have a high yield in CMP processes by quickly producing a uniformlyplanar surface at a desired endpoint on a substrate assembly. Forexample, when a conductive layer on a substrate assembly isunder-planarized in the formation of contacts or interconnects, many ofthese components may not be electrically isolated from one anotherbecause undesirable portions of the conductive layer may remain on thesubstrate assembly over a dielectric layer. Additionally, when asubstrate assembly is over planarized, components below the desiredendpoint may be damaged or completely destroyed. Thus, to provide a highyield of operable microelectronic devices, CMP processing should quicklyremove material until the desired endpoint is reached.

The web-format machine 10 produces good results in applications that usea stationary planarizing pad 40 and orbit the substrate assembly 12about the offset axis B—B. One problem of CMP processing that theplanarizing machine 10 addresses is the center-to-edge planarizingprofile produced by conventional planarizing machines that have arotating platen and a substrate holder that rotates about the centerpoint of the substrate. In conventional rotating platen machines, therotation of both the planarizing pad and the substrate holder causes therelative velocity between the substrate assembly and the pad to beconsistently higher at the perimeter of the substrate assembly than thecenter. The polishing rate accordingly varies from the center of thesubstrate assembly to the perimeter causing a center-to-edge planarizingprofile. The web-format machine 10 reduces the center-to-edgeplanarizing profile by orbiting the substrate holder 32 about the offsetaxis B—B and holding the planarizing pad 40 stationary to reduce thedifference in relative velocity between the substrate assembly 12 andthe pad 40 across the surface of the substrate assembly 12.

The web-format planarizing machine 10 also produces highly planarsurfaces when substrate assemblies are planarized on a fixed-abrasiveplanarizing pad 40 and a “clean” planarizing solution 44, i.e., aplanarizing solution without abrasive particles. Because the abrasiveparticles are fixedly bonded to the pad 40, the particles cannotagglomerate in the planarizing solution or accumulate on the planarizingsurface in waste matter accumulations. The fixed distribution ofabrasive particles on the pad also provides a desired distribution ofabrasive particles under the substrate assembly that is not a functionof the distribution of the planarizing solution under the substrateassembly. Thus, the planarizing machine 10 is particularly useful inapplications that orbit a substrate across a stationary fixed-abrasivepad in the presence of a clean planarizing solution.

Although the web-format planarizing machine 10 is particularly usefulfor fixed-abrasive applications with clean planarizing solutions, it mayalso be desirable to use the web-format machine 10 with non-abrasiveplanarizing pads and slurries having abrasive particles. One reason forusing the planarizing machine 10 with non-abrasive pads and abrasiveslurries is that fixed-abrasive planarizing pads and clean planarizingsolutions may not be available for the structures and chemistriesrequired for many CMP applications. For example, fixed-abrasive pads andclean solutions used to planarize a metal layer of aluminum, copper,tungsten, or titanium in the formation of highly conductiveinterconnects are not widely available for the web-format machine 10.Thus, many CMP applications may require the use of web-format machines10 with non-abrasive pads and abrasive slurries.

One drawback of CMP, and particularly the planarizing machine 10, isthat it is difficult to planarize metal layers using non-abrasive padsand abrasive slurries. CMP of metal layers generally involves oxidizingthe surface of the metal layer with oxidants in the slurry, and removingthe oxidized metal ions from the metal layer with the abrasive particlesin the slurry. The metal ions removed from the substrate 12, however,may become reattached to the substrate 12 where they can create currentleakage paths or other defects. In applications with high ionizationrates or in which the slurry accumulates on the polishing pad, thelikelihood that metal ions will reattach to the substrate surfaceincreases because the concentration of metal ions in the slurryincreases. Thus, planarizing metal layers using the web-formatplanarizing machine 10 or machines having slow moving polishing pads maycause significant defects that reduce the yield of operablemicroelectronic devices.

Another drawback of planarizing substrate assemblies using nonabrasivepads and abrasive slurries is that the abrasive particles may accumulateon the pad or agglomerate in the slurry. These problems are particularlypresent when planarizing metal layers on the stationary pad of theweb-format planarizing machine 10. The accumulations of abrasiveparticles on the planarizing pad 40 typically alter the abrasiveness ofthe planarizing pad, and thus they also alter the consistency of thepolishing rate across the planarizing pad. Additionally, theagglomerations of the abrasive particles in the slurry may alter theabrasiveness of the slurry. In extreme cases, the agglomerations of theabrasive particles in the slurry may scratch the surface of thesubstrate 12. Therefore, the web-format planarizing machine 10 may notproduce sufficiently planar substrate assemblies and/or may producedefects in the substrate assemblies when planarizing metal layers withnon-abrasive planarizing pads and abrasive slurries.

SUMMARY OF THE INVENTION

The present invention is directed toward apparatuses and methods forplanarizing a microelectronic-device substrate assembly on a planarizingpad. In one aspect of the invention, material is removed from thesubstrate assembly by pressing the substrate assembly against aplanarizing surface of a planarizing pad and moving the substrateassembly across the planarizing surface through a planarizing zone. Themethod also includes replacing at least a portion of a used volume ofplanarizing solution on the planarizing surface with fresh planarizingsolution during the planarization cycle of a single substrate assembly.The used planarizing solution can be replaced with fresh planarizingsolution by actively removing the used planarizing solution from the padwith a removing unit and depositing fresh planarizing solution onto thepad in the planarizing zone. The used planarizing solution, for example,can be removed either while the substrate assembly is moved through theplanarizing zone, or between planarizing stages of a multi-stageplanarizing process.

In another aspect of the invention, a planarizing machine forplanarizing microelectronic-device substrate assemblies includes a tablewith a support panel, a planarizing pad attached to the support panel toremain stationary during a planarizing cycle, and a carrier assemblyhaving a substrate holder positionable over the planarizing pad. Theplanarizing pad has a planarizing surface facing away from the supportpanel, and the carrier assembly has a planarizing solution dispenser todispense a fresh planarizing solution onto the planarizing surface. Thecarrier assembly translates the substrate assembly over the planarizingzone of the planarizing surface during a planarizing cycle, and thesubstrate assembly pushes used planarizing solution deposited onto theplanarizing pad into one or more accumulation zones on the pad. Theplanarizing machine also includes a planarizing removing unit at theaccumulation zone to actively remove used planarizing solution from theaccumulation zone on the stationary planarizing pad.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevational view of a web-format planarizingmachine in accordance with the prior art.

FIG. 2 is a schematic isometric view partially illustrating a web-formatplanarizing machine with a planarizing solution removing unit inaccordance with an embodiment of the invention.

FIG. 3 is a schematic cross-sectional view partially illustrating amicroelectronic-device substrate assembly being planarized at one stageof a method in accordance with an embodiment of the invention.

FIG. 4 is a schematic isometric view partially illustrating a web-formatplanarizing machine with another planarizing solution removing unit inaccordance with another embodiment of the invention.

FIG. 5 is a schematic isometric view partially illustrating stillanother web-format planarizing machine with a continuous planarizingsolution removing unit in accordance with still another embodiment ofthe invention.

FIG. 6 is a schematic cross-sectional view of the web-format planarizingmachine of FIG. 5.

FIG. 7 is a schematic isometric view partially illustrating yet anotherweb-format planarizing machine with another planarizing solutionremoving unit in accordance with another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure describes planarizing machines and methods formechanical and/or chemical-mechanical planarizing of substrateassemblies used in the fabrication of microelectronic devices. Manyspecific details of certain embodiments of the invention are set forthin the following description, and in FIGS. 2-7, to provide a thoroughunderstanding of the embodiments described herein. One skilled in theart, however, will understand that the present invention may haveadditional embodiments, or that the invention may be practiced withoutseveral of the details described in the following description.

FIG. 2 is a schematic isometric view partially illustrating a web-formatplanarizing machine 110 for planarizing a substrate 12 in accordancewith one embodiment of the invention. The planarizing machine 110 has atable 14 with a top-panel 16, a carrier assembly 30 for carrying thesubstrate 12, and an operative portion of a web-format planarizing pad40 on the top-panel 16. The planarizing pad 40 also generally haspre-operative and post-operative portions wrapped around supply andtake-up rollers (not shown in FIG. 2). The carrier assembly 30, theplanarizing pad 40 and the supply and take-up rollers can be similar tothose described above with respect to the planarizing machine 10 in FIG.1. The planarizing pad 40 accordingly remains stationary duringplanarization, and a planarizing fluid 44 flows through a plurality ofnozzles 33 onto the planarizing surface 42 of the planarizing pad 40.Unlike the planarizing machine 10, however, the web-format planarizingmachine 110 also includes a removing unit 180 for actively removing usedplanarizing solution from the planarizing pad 40.

The embodiment of the removing unit 180 shown in FIG. 2 has an actuator182 attached to the gantry 34 and a rotating brush 184 coupled to theactuator 182. The brush 184 is generally a non-abrasive brush with aplurality of bristles 185. In a preferred embodiment, the bristles 185are approximately 0.125-0.5 inch strands of polyvinyl alcohol or othersuitable materials that do not abrade or scratch the planarizing pad 40.The bristles 185 are also preferably packed together in a high density.In alternative embodiments (not shown), the brush 184 can be a fixedbrush with bristles that project downward from an arm coupled to theactuator 182, or a wiper blade can be attached to the arm.

In operation, the carrier assembly 30 lifts the substrate 12 from thepad 40, and then the actuator 182 rotates the brush 184 (arrow R) andsweeps the brush 184 (arrow S) across the planarizing surface 42. Theactuator 182 preferably sweeps the brush 184 across the pad 40 in adirection counter to the rotation R of the brush 184 at the planarizingsurface 42. As the actuator 182 sweeps the brush 184 across theplanarizing surface 42, the bristles 185 wipe used planarizing solutionon the planarizing surface 42 into a trough 186 (arrow W) to remove usedplanarizing solution from the pad 40. The trough 186 channels theplanarizing solution removed from the pad (arrow D) to a reservoir (notshown).

One method for operating the planarizing machine 110 is a multistageplanarizing process in which a planarizing cycle of a single substratehas a first stage to remove material from the substrate 12 to anintermediate level, a cleaning stage to remove used or residualplanarizing solution from the pad 40, and a second stage to removeadditional material from the substrate 12 with fresh planarizingsolution 44. At the first-stage of the planarizing process, the carrierassembly 30 presses the substrate 12 against planarizing surface 42 andmoves the substrate 12 through a planarizing zone 46 until the surfaceof the substrate 12 reaches an intermediate point prior to the finaldesired endpoint of the substrate 12. During the first-stage of theplanarizing process, an initial batch of planarizing solution 44 flowsthrough the nozzles 33 onto the pad 40, and the substrate 12 pushes atleast a portion of the initial batch of planarizing solution 44 out ofthe planarizing zone 46 and into outer and inner accumulation zones 48 aand 48 b. Since the pad 40 is stationary, a portion of the usedplanarizing solution 44 in the accumulation zones 48 a and 48 b flowsback into the areas of the planarizing zone 46 that are not occupied bythe substrate assembly 12. The characteristics of the planarizingsolution 44 in the planarizing zone 46 accordingly change throughout thefirst stage of the planarizing process because residual materials fromthe substrate 12, the pad 40, and/or the planarizing solution 44accumulate in the used planarization solution. Thus, the duration of thefirst stage of the process is generally less than the time it takes toalter the planarizing properties of the planarizing solution to a pointat which the planarizing solution does not provide consistent results.To restore the planarizing solution to a suitable state, the first stageof the planarizing cycle is terminated and the used planarizing solution44 is removed from the pad 40 by sweeping the rotating brush 184 acrossthe planarizing surface 42, as described above.

The carrier assembly 30 then commences the second stage of theplanarizing process for the substrate 12 by depositing new or additionalplanarizing solution 44 onto the planarizing surface 42 to replace theused planarizing solution that was removed by the brush 184. The carrierassembly 30 also translates the substrate 12 through the planarizingzone 46 in the presence of the fresh planarizing solution 44 until thefinal endpoint of the substrate assembly is reached. The second stage ofthe planarizing cycle is generally much shorter than the first stage,but the second stage may be approximately equal to the length of thefirst stage or even longer than the length of the first stage.Additionally, the multi-stage process for operating the planarizingmachine 10 may have more than two planarizing stages and more than onecleaning stage.

The planarizing machine 110 and the multi-stage planarizing process forplanarizing the substrate 12 on the planarizing machine 110 areparticularly well suited for forming damascene interconnect lines orother metal structures on a substrate assembly. FIG. 3 is a schematiccross-sectional view of forming damascene interconnect lines on thesubstrate 12 during the first stage of the multi-stage process describedabove. In this particular embodiment, the substrate 12 has a dielectriclayer 13 with a plurality of grooves 15 that are filled by a metal coverlayer 17. The metal cover layer 17 can be composed of aluminum, copper,tungsten, titanium, titanium nitride or other suitable metals. When themetal layer 17 is composed of aluminum, the substrate assembly 12 ispreferably planarized using either a conventional CMP slurry or afixed-abrasive pad having alumina abrasive particles 45.

The first stage of the two-stage process involves translating thealuminum cover layer 17 of the substrate 12 across the planarizingsurface 42 for approximately 60-200 seconds, and preferably forapproximately 100 seconds. The planarizing solution 44 typicallyoxidizes the surface of the cover layer 17, and the alumina abrasiveparticles 45 remove the oxidized portion of the cover layer 17. Theionic form of the metal cover layer 17 accordingly enters theplanarizing solution 44. As the first stage proceeds, the usedplanarizing solution accumulates on the pad causing the concentration ofmetal ions in the solution to increase. The first stage of the process,however, is terminated before the ionic strength of the planarizingsolution reaches a threshold level at which the metal ions in theplanarizing solution can become significantly reattached to the surfaceof the substrate 12. The first stage is also terminated before the ionicstrength of the planarizing solution reaches a threshold at which thealumina abrasive particles accumulate on the pad 40 or significantlyagglomerate in the planarizing solution 44. The used planarizingsolution 44 on the planarizing pad 40 from the first stage is thenremoved with the brush 184, as described above with respect to FIG. 2.

The second stage of the two-stage process then commences by depositingfresh planarizing solution 44 onto the planarizing surface 42 to replacethe used planarizing solution 44 with a planarizing solution having alower ionic strength. The second stage of the process also involvesmoving the substrate 12 across the planarizing surface for approximately20-60 seconds, and preferably for approximately 50 seconds. The secondstage generally continues until the surface of the substrate 12 is at afinal endpoint E at which the aluminum in the grooves 15 forms damascenelines that are electrically isolated from one another by the dielectriclayer 13.

The planarizing machine 110 and the multi-stage method of planarizingthe substrate assembly 12 provide good results for planarizing metallayers using stationary non-abrasive pads and abrasive slurries, andalso with fixed-abrasive pads and clean solutions. One aspect of theinvention is the recognition that metal ions removed from the substratetend to redeposit back onto the substrate when the ionic strength of thesolution increases to a threshold where the electrostatic charge betweenthe substrate and the slurry attracts the metal ions back to the surfaceof the substrate. The multi-stage process maintains the ionic strengthof the planarizing solution on the planarizing pad below such athreshold by removing an initial batch of used planarizing solution fromthe planarizing pad before the ionic strength of the solution reachessuch a threshold, and then depositing a new batch of planarizingsolution at a lower ionic strength to continue planarizing thesubstrate. The multi-stage process may accordingly have more than twostages because it may be necessary to use three or more new batches ofplanarizing solution on the planarizing pad to maintain the ionicstrength of the planarizing solution below such a threshold level.Therefore, the planarizing machine 110 and the multi-stage process foroperating the planarizing machine 10 is expected to substantiallyprevent redeposition or reattachment of metal ions back onto thesubstrate 12.

The planarizing machine 110 and the multi-stage method for operating theplanarizing machine 110 also provide good results for CMP of metallayers because the ionic strength of the slurry can be maintained belowthe threshold level at which abrasive particles agglomerate in theslurry or accumulate on the planarizing pad. Another aspect of theinvention is the recognition that the increase in the ionic strength ofthe planarizing solution causes the abrasive particles in the slurry toaccumulate on the pad and agglomerate in the slurry. The multi-stageprocess for operating the planarizing machine 110 prevents the ionicstrength of the planarizing solution from increasing to such athreshold. Therefore, the planarizing machine 110 and the multi-stagemethod for operating the planarizing machine 110 are also expected toenhance the consistency of the slurry.

FIG. 4 is a schematic isometric view partially illustrating aplanarizing machine 210 with a planarizing solution removing unit 280for intermittently removing used planarizing solution 44 from the pad 40in accordance with another embodiment of the invention. In thisembodiment, the removing unit 280 has an actuator 282 attached to thegantry 34 and a vacuum assembly 284 coupled to the actuator 282. Thevacuum assembly 284 has an elongated nozzle 285 that rests upon theplanarizing surface 42. The vacuum assembly 284 can also have a vacuumsource (not shown) coupled to the nozzle 285.

In operation, the actuator 282 sweeps the nozzle 285 across theplanarizing surface 42 as the vacuum source draws a vacuum through thenozzle 285. The vacuum assembly accordingly sucks the used planarizingsolution 44 from the pad 40. The planarizing machine 210 is preferablyused between stages of a multi-stage planarizing process as describedabove. For example, the substrate 12 is planarized on the planarizingsurface 42 to an intermediate point during a first stage, and then thecarrier assembly 30 lifts the substrate assembly 12 from the planarizingsurface 42 so that the vacuum assembly 284 can sweep across theplanarizing surface and remove the used planarizing solution 44 from theplanarizing pad 40. After the vacuum assembly 284 is cleared from theplanarizing zone 46, the carrier assembly 30 reengages the substrate 12with the planarizing surface 42 and deposits fresh planarizing solutiononto the planarizing pad 40 to perform the second stage of the processin which additional material is removed from the substrate 12 to thefinal endpoint. It is expected that the advantages of the planarizingmachine 210 with the removing unit 280 are substantially the same asthose described above with respect to the planarizing machine 110 withthe removing unit 180.

FIG. 5 is a schematic isometric view partially illustrating aplanarizing machine 310, and FIG. 6 is a schematic cross-sectional viewof the planarizing machine 310, in accordance with another embodiment ofthe invention. The planarizing machine 310 has a supply roller 20, atake-up roller 23, and a carrier assembly 30 as described above. Theplanarizing machine 310 also has a planarizing pad 340 with aplanarizing surface 342 including a plurality of holes 343 in theaccumulation zone 48 a. The planarizing machine 310 also has a removingunit 380 including a plurality of holes 384 in the panel 16 coupled to acommon conduit 386. A vacuum source 387 can be coupled to the conduit386 and the holes 384 via a valve 388.

The planarizing machine 310 can be operated in a multi-stage process asdescribed above, or it can be operated in a continuous process in whichused planarizing solution in the accumulation zone 48 a is drawn throughthe holes 343 and 384 by the vacuum 387 to remove the used planarizingsolution 44 from the planarizing pad while the substrate 12 is beingplanarized. The rate at which the removing unit 380 draws the usedplanarizing solution through the holes 343 is preferably controlled tomaintain the planarizing characteristics of the planarizing solution ata desired level. For example, in the case of metal CMP, the carrierassembly 30 deposits fresh planarizing solution 44 and the removing unit380 removes used planarizing solution in a manner that maintains theionic charge of the planarizing solution on the planarizing pad 340below the threshold at which ions significantly redeposit onto thesubstrate 12, or the threshold at which abrasive particles significantlyagglomerate in the planarizing solution or accumulate on the planarizingpad 40.

In an alternative embodiment, the planarizing pad 340 also has aplurality of holes 345 in the inner accumulation zone 48 b, and theremoving unit 380 has a plurality of holes 385 under the inneraccumulation zone 48 b. The removing unit 380 in this embodimentaccordingly removes used planarizing solution from both the outer andinner accumulation zones 48 a and 48 b, respectively, duringplanarization of the substrate 12. In still another embodiment, theplanarizing pad 340 can be a porous planarizing pad without the holes343 and 345. In this embodiment, the vacuum draws the used planarizingfluid 44 through the pores of the planarizing pad and through the holes384 and 385 in the table 16.

The planarizing machine 310 is also expected to provide good results forCMP of metal layers and other materials because it can continuouslymaintain the ionic strength of the planarizing solution on theplanarizing pad below the threshold at which substrate materialssubstantially redeposit onto the substrate, or the threshold at whichabrasive particles substantially agglomerate in the planarizing solutionor substantially accumulate on the planarizing pad. Additionally, theplanarizing machine 310 may provide continuous planarization of thesubstrate 12 without interrupting the planarizing cycle tointermittently remove used planarizing solution from the pad 40.Therefore, the planarizing machine 310 is expected to enhance theplanarity of the finished substrates without increasing the time for theplanarizing cycles.

FIG. 7 is a schematic isometric view partially illustrating aplanarizing machine 410 for continuously planarizing the substrate 12 onthe planarizing pad 40 in accordance with another embodiment of theinvention. The planarizing machine 410 has a continuous removing unit480 attached to an arm 438 of the carrier assembly 30. The arm 438 isgenerally longer than the arm 38 shown in FIG. 2 such that the driveshaft 37 is attached to the mid-point of the arm 438. The removing unit480 preferably has a shaft 484 attached to the arm 438 at an endopposite from the shaft 39 carrying the substrate holder 32, and awiping element 482 extending from the shaft 484. The wiping element 482extends transverse to the outer and inner accumulation zones 48 a and 48b, and the wiping element 482 is spaced apart from the substrate 12. Inone embodiment, the wiping element 482 is a rotating brush similar tothat set forth above with respect to the planarizing machine 110. Inanother embodiment, the wiping element 482 is a vacuum assembly with anozzle similar to that described above with respect to the planarizingmachine 210. In still another embodiment, the wiping element is a wiperblade.

The planarizing machine 410 continuously removes used slurry from theplanarizing pad 40 as the substrate 12 is being planarized. Moreparticularly, the carrier assembly 30 rotates the arm 438 to translateboth the wiping element 482 and the substrate 12 across the planarizingsurface 42 of the pad 40. The wiping element 482 continuously removesused planarized solution 44 from at least a portion of the accumulationzones 48 a and 48 b as the substrate 12 passes over newly depositedplanarizing solution 44 in the planarizing zone 46. Furthermore, bymounting the substrate holder 32 and the removing unit 480 at oppositeends of the arm 438, the substrate holder 32 and the removing unit 480do not interfere with the operation of each other. The planarizingmachine 410 accordingly provides good results for CMP of metal layersand other materials using stationary non-abrasive pads and abrasiveslurries in a manner similar to that discussed above with respect to theplanarizing machine 310.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

What is claimed is:
 1. A planarizing machine for planarizingmicroelectronic-device substrate assemblies in a web format machine,comprising: a table with a support panel; a planarizing pad on the webformat machine including a planarizing surface facing away from thesupport panel, the planarizing pad being removably attached to thesupport panel; a carrier assembly having a substrate holder positionableover the planarizing pad and a planarizing solution dispenser todispense a fresh planarizing solution onto the planarizing surface, thesubstrate holder translating a substrate assembly over a planarizingzone of the planarizing surface during a planarizing cycle, and thesubstrate assembly pushing used planarizing solution deposited onto theplanarizing pad into an accumulation zone on the planarizing surfaceadjacent to the planarizing zone; and a planarizing solution removingunit at the accumulation zone, the removing unit being coupled to anactuator to translate the removing unit across the pad while the pad isheld stationary to actively remove used planarizing solution from atleast a portion of the accumulation zone on the stationary planarizingpad.
 2. The planarizing machine of claim 1, further comprising a vacuumassembly attached to the actuator separate from the carrier assembly,the vacuum assembly having a nozzle adapted to engage the planarizingsurface of the pad, and the actuator sweeping the nozzle over at least aportion of the accumulation zone.
 3. A planarizing machine forplanarizing microelectronic-device substrate assemblies in a web formatmachine, comprising: a table; a planarizing pad on the web formatmachine removably attached to the table having a planarizing surfacefacing away from the table; a carrier assembly having a substrate holderpositionable over the planarizing pad and a planarizing solutiondispenser to dispense a fresh planarizing solution onto the planarizingsurface, the substrate holder translating a substrate assembly over aplanarizing zone of the planarizing surface during a planarizing cycleto move used planarizing solution deposited onto the planarizing padinto an accumulation zone on the planarizing surface adjacent to theplanarizing zone; and a planarizing solution removing unit at theaccumulation zone, the removing unit being coupled to an actuator totranslate the removing unit across the pad while the pad is heldstationary to at least partially remove used planarizing solution fromthe accumulation zone on the stationary planarizing pad.
 4. Theplanarizing machine of claim 3 wherein the vacuum assembly includes anozzle positionable in the accumulation zone to be exposed to at least aportion of the used planarizing solution and a vacuum source coupled tothe nozzle to draw the used planarizing solution through the nozzle. 5.A planarizing machine, for planarizing microelectronic-device substrateassemblies in a web format machine having a planarizing pad removablyattached to a table and having a planarizing surface facing away fromthe table, comprising: a carrier assembly having a substrate holderpositionable over the planarizing pad on the web format machine and aplanarizing solution dispenser configured to distribute freshplanarizing solution onto the planarizing surface, the substrate holdertranslating a substrate assembly over a planarizing zone of theplanarizing surface during a planarizing cycle to move used planarizingsolution on the planarizing pad into an accumulation zone on theplanarizing surface adjacent to the planarizing zone; and a planarizingsolution removing unit at the accumulation zone, the removing unit beingcoupled to an actuator to translate the removing unit across the padwhile the pad is held stationary to at least partially remove usedplanarizing solution from the accumulation zone on the stationaryplanarizing pad.
 6. The planarizing machine of claim 5 wherein thevacuum assembly includes a nozzle positionable in the accumulation zoneto be exposed to at least a portion of the used planarizing solution anda vacuum source coupled to the nozzle to draw the used planarizingsolution through the nozzle.